In the Following some Sections you are going to know about the main or Key Components of a Laser Printer which are as Follows :
Laser
In laser printers, the Laser component is fundamental to the operation of the machine and is in effect a laser gun, controlled by the electronics which fires pulses of light at mirrors inside the printer. These mirrors bounce the light onto a photosensitive drum to form the image you are creating as static electricity.
Imaging Unit
Often referred to as the Drum or photoconductor unit, the imaging unit is a normally an aluminium cylinder which has been coated with a light sensitive film. This film reacts to the light bounced from the mirrors to create an image on the drum. This image takes the form of areas of charged static electricity (created by the charge corona) and the intensity of the light dictates the amount of colour, grey, black or white used on the original document.
Charge Corona: Normally integrated within the imaging unit the charge corona is a thin wire within a metal casing that produces an electrical charge on the drum where the light reacts with the light sensitive coating. The purpose of this charge is to attract the positively charged toner onto the drum to create a copy or copies of the original document.
Toner Cartridges
Contained within a cartridge for ease of handling, toner is finely ground plastic powder that has been dyed, black, cyan, magenta or yellow, when heated; this powder becomes ink. In most instances a finely ground metallic chemical (the developer) that can be electrically charged is also incorporated so that when the electrically charged drum passes the toner cartridge, the developer / toner mix is attracted onto the drum.
In color printers a number of toner cartridges, each containing a different color of toner powder sit parallel to the drum to enable good color rendering.
Fuser Unit
Normally, the fuser unit comprises two rollers, the upper roller is heated and is designed to melt the thin film of toner plastic, enabling the ink to be transferred to the paper as it passes between the rollers.
Heated by a temperature controlled lamp, the upper fuser roller is coated with a non-stick silicon coating that can be easily cleaned. The lower roller does not need to be heated and is usually made from soft silicon rubber which holds the paper and helps ensure smooth passage between the rollers.
Paper Transport
The paper path for laser printers ranges from a simple, straight path to the complicated turns of devices with options such as duplexers, mailboxes, and finishing tools like collators and staplers. The goal is the same for all these devices-to move the paper from a supply bin to the engine where the image is laid on the paper and fixed to it, and then to a hopper for delivery to the user. Most printers handle a set range of paper stocks and sizes in the normal paper path, and a more extensive range (usually heavier paper or labels) that can be sent though a second manual feed, one sheet at a time. When users fail to follow the guidelines for the allowed stocks, paper jams often result.
Logic Circuits
User Interface
The basic laser printer often offers little more than a "power on" LED and a second light to indicate an error condition. Advanced models have LED panels with menus, control buttons, and an array of status LEDs.
Toner and Toner Cartridges
To reduce maintenance costs, laser printers use disposable cartridges and other parts that need periodic replacement. The primary consumable is toner, a very fine plastic powder bonded to iron particles. The printer cartridge also holds the toner cylinder, and often the photosensitive drum. The cartridge requires replacement when the level of toner is too low to produce a uniform, dark print. Some "starter" cartridges shipped with a new printer print only 750 sheets or so, while high-capacity units can generate 12,000 or more pages. Keep in mind that what constitutes a "page" is based on a five-percent coverage area, less than a standard letter and far below that of a page of graphics or images.
Photosensitive Drum
The photosensitive drum is a key component and usually is a part of the toner cartridge. The drum is an aluminum cylinder that is coated with a photosensitive compound and electrically charged. It captures the image to be printed on the page and also attracts the toner which is to be placed on the page.
Primary Corona
The primary corona charges the photosensitive particles on the surface of the drum.
Transfer Corona
The transfer corona charges the surface of the paper just before it reaches the toner area.
Fuser Rollers
The toner must now be permanently attached to the paper to make the image permanent. The fuser rollers-a heated roller and an opposing pressure roller-fuse toner onto the page. The heated roller employs a nonstick coating to keep the toner from sticking to it. The occasional cycling heard in many laser printers is generated when the fuser rollers are advanced a quarter turn or so to avoid becoming overheated.
Erase Lamp
This bathes the drum in light to neutralize the electrical charge on the drum, allowing any remaining particles to be removed before the next print is made.
Power Supply
Laser printers use a lot of power and so should not be connected to a UPS (uninterruptible power supply) device. The high voltage requirements of the imaging engine and heater will often trip a UPS. In addition to the motors and laser print heads, the printer also has a low DC voltage converter as part of the power package for powering its motherboard, display panel, and other more traditional electronic components.
Drivers and Software
Most laser printers ship with a variety of software that includes the basic drivers that communicate with the operating system, diagnostic programs, and advanced programs that allow full control of all options as well as real-time status reporting. A recent trend in network laser printing is allowing print-management tools and printing to work over the Internet. A user can send a print job to an Internet site or manage a remote print job using a Web browser.
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